It doesn't matter if the tape is light tight. The flap itself is the light trap. Bookbinding tape lasts longer and is more flexible than gaffers' tape and makes the holders much more pleasant to load. The flap won't keep flipping up into your way.Originally Posted by Fr. Mark
-Chris
I have tried to replace some light traps on old holders, and noticed some stuff...
The Velcro idea seemed good at first, but in practice turned out that some tiny pinholes of light can go through the mesh, but probably ok for indoor use...
Tried some foam tapes as a spring under felt, but almost worked as the foam took a short interval to completely decompress, so a light danger, but closed cell rubber responds instantly... I think I ended up using wet suit neoprene...
Be careful to not allow the leading or trailing edge of the trap to come near the slide as this can cause these to start rolling up and jamming or rolling against the slide...
The old metal spring under the felt traditional method can lay the flattest...
Make sure to polish leading and side edges of slides to prevent them cutting up trap over time...
Run some tests before you make a final decision, and consider time and wear might change these...
Steve K
Thanks Fr. Mark, I have thought about magnets. I even bought a roll of magnetic material with an adhesive back, but it is too thick--about 1/16th, IIRC. And very weak. I would also be concerned about magnets (or metal) getting jostled during transit, hiking, etc.
Right now, I'm still experimenting with the 3M double sided tape. If that fails, I will probably try gluing in wooden film guides--at least for three sides and use the tape on what would be the flap end.
Yes, I've noticed this as well. Currently, I'm using internal springs but I do not have a recessed area on the underside of the baffle cover. In lieu of machining out a recessed area, I'm thinking about adding a thin strip of adhesive felt to the front edge of the baffle cover. The felt is about 1/16th in.
Right on, C.D. I also use bookbinding tape for replacing the tape on worn flaps on older wooden holders. Works great.
Yes, Steve, thanks. I had the same problem with velcro. Also tried foam, with similar results. The brass springs I'm currently using seem to work well. I covered the brass springs with black felt, and I painted the leading edge of the felt with black fabric paint since the felt by itself is not light proof.
In addition to sanding the edges of the dark slides, I polish them with wax paper so they slide easier.
Just back from a trip to Moab. I had one success and one fail with one of my adhesive holder prototypes. After giving the fail side a good look, I "may" have discovered the problem--the tape I applied does not extend all the way to the edge of the plenum nearest the baffle. This is allowing the edge of the film to curl up and--after making an exposure--when I re-insert the dark slide, the slide is catching the underside of the film and peeling the rest of the film sheet away from the plenum.
At least, this is what it feels like and is my latest working hypothesis.
I will add an additional strip of tape flush against the baffle end of the plenum and test it out.
Boy, if this works, I'll be golden.
If not, back to the old drawing board....
[note to self: 928=9416
9416+9425=success?]
Last edited by Michael Roberts; 14-Apr-2020 at 14:55.
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